1. Physical Science Chapter 3
Energy

2. The Nature of Energy
Energy – the ability to do work or cause a change.
Two main types of energy: Kinetic and Potential
Kinetic Energy: the energy of motion
Potential Energy: Energy stored for use at a later time

3. Forms of Kinetic Energy
Mechanical
Thermal
Electrical
Radiant / Electromagnetic
Sound

4. GPE = mass x gravity x height
Mechanical Energy
Movement of an object or it’s parts (based on amount of PE)
GPE = mass x gravity x height

5. Thermal Energy
total energy of the particles (atoms and molecules) in an object
TE Increases = particle speed up, temperature up, overall KE up

7. Electrical Energy Passing of electrons as a current
Flow of electricity through a conductor

8. Radiant / Electromagnetic energy
Travels on waves – NO matter needed to pass the energy
light, infrared, ultraviolet, microwaves, x-rays, etc…
Longer wavelength = low frequency & low energy (Red)
Shorter wavelength = high frequency & high energy (Violet)

10. Sound
Vibration of particles
CANNOT move in empty space – NEED matter

11. Calculating Kinetic Energy
NEED TO KNOW - mass and speed (velocity)
Energy is transferred during work
The more work one does on an object…
The more energy one imparts on the object
Kinetic energy = Mass x Velocity2 2
***When mass is doubled; Kinetic Energy is doubled
***When velocity is doubled; Kinetic Energy is quadrupled!!

12. What’s the Kinetic Energy?
What is the Kinetic Energy (in Joules) of an object with a mass of 10 kg and a velocity of 10 m/s?
When mass is doubled; Kinetic Energy is doubled
When velocity is doubled; Kinetic Energy is quadrupled!!

13. Practice
Velocity = Speed (distance/time) Unit = m/s
Mass = you know this Unit = g or kg
Joules = Amount of Energy Unit = J (1kg, 1m, 1sec)
Mounted TV falls to the floor – How much KE did it have? M = 20 kg V = 2m/s KE = ½ m x v2
2. Skateboarder travels down a ramp – How much KE does she have? M = 65 kg V = 35m/s

14. Forms of Potential Energy
Gravitational GPE
Chemical
Elastic
Nuclear
Magnetism

15. Chemical Energy stored in chemical bonds
Bonds break/combine = release of energy

16. Gravitational (GPE)
Stored above the ground or work done to lift an object above the ground
Higher Elevation = Higher GPE
Greater Mass = Higher GPE
m = mass g = gravity acceleration (10m/s2) h = height
GPE = mgh
GPE = mass x 10 m/s2 x height
Increase mass or height = increase in GPE

17. Practice - (N) Newtons = Mass on Earth  Pull of Gravity
(1 N = .25 lbs) Unit = N
(h) Height = You Know This Unit = meters
Rock sitting on a hill – What is GPE?
m = 100 N g = 10 m/s h = 300 m GPE = mgh
2. TV mounted on wall – What is GPE?
m = 196N g = 10 m/s h = 2.5 m

18. Magnetism
Magnetic fields/force
Attract/repel objects

19. Elastic Objects that can be stretched or compressed
Energy stored in springs, bow and arrow, stretched elastic or rubber bands.

20. Nuclear Energy Stored in subatomic particles (neutrons of an atom)
The fusion of hydrogen into helium fuels the power of the sun

22. LAW OF CONSERVATION OF ENERGY
Closed System
Not Created or Destroyed
Only Changes Forms
100% in = 100% out
Most energy is lost to friction or thermal energy
PHET.COM

23. Energy Efficiency Unwanted Energy * useful energy is less than total
* Thermal/heat, friction, sound
What is Efficient???
* more useful energy – less unwanted

25. Needed Improvements

28. ENERGY CONVERSIONS Transformation Transfer
Converts from one form to ANOTHER form
Transfer
Converts from one form to the SAME form

31. DIAGRAMS: Solar to Running

32. DIAGRAMS: Coal Power Plant

33. DIAGRAMS: Hydroelectric Power Plant

34. DIAGRAMS: Nuclear Power Plant

35. DIAGRAMS: Wind Power